Issue 70 - Meet peat

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Meet peat

In the latest in his series on whisky terms,Dominic Roskrow addresses part one of a two part look at the letter P, and makes sense of peat,phenols and PPMs

Whisky is defined as a spirit made with grain, yeast and water only, and a single malt whisky as one made at one distillery using only malted barley,water and yeast.

With the exception of allegedly flavourless caramel colouring, nothing else may be added to malt whisky.

This, though, isn't the whole story. One of the key components to some of the world's greatest whiskies is, of course,peat,and while it isn't actually added to the whisky-making process, its presence can fundamentally help define the taste of a malt.

Peat's role in the development of the flavours of whisky is twofold; through its presence in natural water and through its use in the drying of barley once it has been soaked in water and ‘tricked' into growing.

Contrary to what many people think, the effect on taste of peat in water is very minimal. It is true that much of Scotland and Ireland's natural water sources pass through peat bogs and often its presence is reflected in the deep brown colour of the water.

But the fermentation and distillation process distance the final spirit from the peat in the original water, and although traces of peat can sometimes be picked up in whisky where no peat-dried barley has been used, it is relatively small.Peat imparts phenols to the malt and these are measured in parts per million (PPM).The effect of peat in the original water has been measured in the final mix as as little as 1PPM.

Peat smoke from the drying process is another matter. It will impart a very high ...